Prehistoric Coffee Ancestor Found in Amber

Fossil flowers found perfectly preserved in amber represent a new plant species that’s a 45-million-year-old relative of coffee, according to new research.

Named Strychnos electri, after the Greek word for amber (electron), the flowers represent the first-ever fossils of an asterid, which is a family of flowering plants that not only later gave us coffee, but also sunflowers, peppers, potatoes, mint — and deadly poisons.

The flowers, described in the journal Nature Plants, belong to the dark side of the family. They are in the genus Strychnos, which ultimately gave rise to some of the world’s most famous poisons, including strychnine and curare. The prehistoric flowers’ attractiveness and incredible state of preservation belie their toxicity.

“The specimens are beautiful, perfectly preserved fossil flowers, which at one point in time were borne by plants that lived in a steamy tropical forest with both large and small trees, climbing vines, palms, grasses and other vegetation,” said Oregon State professor George Poinar, Jr., an expert in plant and animal life forms preserved in amber, in a release.

“Specimens such as this are what give us insights into the ecology of ecosystems in the distant past,” he continued. “It shows that the asterids, which later gave humans all types of foods and other products, were already evolving many millions of years ago.”

Poinar and his team recently made the discovery while analyzing amber that had been collected in the Dominican Republic in 1986. He and his colleagues explained that asterids are among Earth’s most important and diverse plants, with 10 orders, 98 families, and about 80,000 species. They represent about one-third of all the earth’s diversity of angiosperms, or flowering plants.

The new find shows that plants in the very poisonous genus existed for many millions of years before humans evolved from our primate ancestors.

Humans have clearly since put asterids to good use, considering how common the edible ones are in our diets. As for the poisonous plants, their toxic compounds have been added to blow-gun weapons, rat control, and have even been featured in classic murder mysteries such as Sherlock Holmes stories and the movie “Psycho.”

Read more at Discovery News

Mystery 'Hobbits' not Human, Study Says

Diminutive humans that died out on an Indonesian island some 15,000 years ago were not Homo sapiens, but a different species, according to a study published Monday that dives into a fierce anthropological debate.

Fossils of Homo floresiensis — dubbed “the hobbits” due to their tiny stature — were discovered on the island of Flores in 2003.

Controversy has raged ever since as to whether they are an unknown branch of early humans or specimens of modern man deformed by disease.

The new study, based on an analysis of the skull bones, shows once and for all that the pint-sized people were not Homo sapiens, according to the researchers.

Until now, academic studies have pointing in one direction or another — and scientific discourse has sometimes tipped over into acrimony.

One school of thought holds that so-called Flores Man descended from the larger Homo erectus and became smaller over hundreds of generations.

The proposed process for this is called “insular dwarfing” — animals, after migrating across land bridges during periods of low sea level, wind up marooned on islands as oceans rise and their size progressively diminishes if the supply of food declines.

An adult hobbit stood a metre (three feet) tall, and weighed about 25 kilos (55 pounds).

Similarly, Flores Island was also home to a miniature race of extinct, elephant-like creatures called Stegodon.

But other researchers argue that H. floresiensis was in fact a modern human whose tiny size and small brain — no bigger than a grapefruit — was caused by a genetic disorder.

One suspect was dwarf cretinism, sometimes brought on by a lack of iodine. Another potential culprit was microcephaly, which shrivels not just the brain and its boney envelope.

Weighing in with a new approach, published in the Journal of Human Evolution, a pair of scientists in France used high-tech tools to re-examine the layers of the “hobbit” skull.

More precisely, they looked at the remains of Liang Bua 1 (nicknamed LB1), whose cranium is the most intact of nine known specimens.

Mystery solved?

“So far, we have been basing our conclusions on images where you don’t really see very much,” said lead author Antoine Balzeau, a scientist at France’s Natural History Museum.

Joining forces with Philippe Charlier, a palaeopathologist at Paris-Descartes University specialized in solving ancient medical mysteries, the researchers secured high-resolution images recently generated in Japan to compute maps of bone thickness variation.

Read more at Discovery News

Hawking: Gravitational Waves Could Revolutionize Astronomy

In the wake of last week’s historic announcement of the discovery of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO), British physicist and black hole theorist Stephen Hawking was quick to congratulate the US-led collaboration, sharing his excitement for the historic news.

“These results confirm several very important predictions of Einstein’s theory of general relativity,” Hawking said in a BBC interview. “It confirms the existence of gravitational waves directly.”

As is becoming clear, the direct detection of these ripples in spacetime not only confirm Einstein’s famous theory of general relativity, they open our eyes to a previously “dark” universe. Astronomy uses the electromagnetic spectrum (such as visible light, X-rays, infrared) to study the universe, but objects that do not radiate in the electromagnetic spectrum will go unnoticed. But now we know how to detect gravitational waves, there could be a paradigm shift in how we detect and study some of the most energetic cosmic phenomena.

“Gravitational waves provide a completely new way of looking at the universe,” said Hawking. “The ability to detect them has the potential to revolutionize astronomy.”

Using LIGO’s twin observing stations located in Louisiana and Washington, physicists not only detected gravitational waves; the gravitational waves they detected had a very clear signal that closely matched theoretical models of a black hole merger some 1.3 billion light-years away. Already, from initial analysis of the black hole merger signal, Hawking has realized that the system seems to align itself with theories he developed in the 1970′s.

“This discovery is the first detection of a black hole binary system and the first observation of black holes merging,” he said. “The observed properties of this system is consistent with predictions about black holes that I made in 1970 here in Cambridge.”

Hawking is perhaps most renowned for his work on melding quantum theory with black hole physics, realizing that black holes evaporate over time, leading to his involvement in the fascinating "Firewall Paradox" that is continuing to rumble throughout the theoretical physics community. But here he refers to his black hole area theorem, which forms the basis of the “second law” of black hole mechanics. This law states that entropy, or the level of disorganization of information, cannot decrease within a black hole system over time. A consequence of this theorem is that should two black holes merge, like the Sept. 14 event, the combined event horizon area “is greater than the sum of the areas of the initial black holes.” Also, Hawking points out that this gravitational wave signal appears to be in agreement with predictions based on the “no-hair theorem” of black holes, basically meaning a black hole can be simply described by its spin, mass and charge.

The details behind how this first gravitational wave signal of a black hole merger agrees with theory are complex, but it is interesting to know that this first detection has already allowed physicists to confirm decades-old theories that have, until now, had little to no observational evidence.

“This discovery also presents a puzzle for astrophysicists,” said Hawking. “The mass of each of the black holes are larger than expected for those formed by the gravitational collapse of a star — so how did both of these black holes become so massive?”

This question touches on one of the biggest mysteries surrounding black hole evolution. Currently, astronomers are having a hard time understanding how black holes grow to be so massive. On the one end of the scale, there are “stellar mass” black holes that form immediately after a massive star goes supernova and we also have an abundance of evidence for the existence of the supermassive behemoths that live in the centers of most galaxies. There is a disconnect, however.

If black holes grow by merging and consuming stellar matter, there should be evidence of black holes of all sizes. But “intermediate mass” black holes and black holes of a few dozen solar masses are astonishingly rare, throwing some black hole evolution theories into doubt.

Read more at Discovery News

Hubble Studies 'Super-Earth' Atmosphere for First Time

For the first time, a super-Earth’s atmosphere has been analyzed — but don’t make any vacation plans to visit. The planet is blisteringly close to its planet star (exhibiting temperatures of 3,600 Fahrenheit or 2,000 Celsius) and has an atmosphere mostly made up of hydrogen and helium, like a gas giant planet.

Hydrogen and helium are common elements in young solar systems as those are the elements that make up young stars. Typically, however, smaller planets tend to lose the hydrogen and helium over time into space because their gravity is so low; the light elements escape, especially if a star’s radiation pushes against the atmosphere. Gas giant planets can hold on to those elements due to their stronger gravity.

On small planets, sometimes the hydrogen/helium atmosphere is replaced by a secondary atmosphere, which was the case on Earth. Our current mix of nitrogen, oxygen and carbon dioxide likely came from internal processes (such as volcanism) and the evolution of plants.

“We did not expect 55 Cancri e to retain this much of its primordial gas atmosphere,” said Ingo Waldmann, a post-doctoral research assistant at University College London who participated in the research, in an e-mail to Discovery News. Waldmann pointed out that the planet is the only known super-Earth with such a high temperature, but the astronomers had thought it would lose most of its atmosphere due to the intense radiation of its parent star. Why it held on to the hydrogen and helium is poorly understood.

Astronomers have a few sample measurements of planetary atmospheres from outside our solar system, but these are from gas giants that are easier to spot in telescopes. As the large planet passes across the face of its planet star, the elements detected in a telescope change slightly. That change is believed to represent the atmosphere of the planet.

The team decided to try for a smaller planet, but one that was orbiting a bright star to make it easier to distinguish the atmosphere of the planet from the elements in its parent star. A strong candidate for this work was the Hubble Space Telescope’s Wide Field Camera 3, which was installed by astronauts in 2009 and usually is used to track star or galaxy formation.

“The WFC3 camera on Hubble is a very sensitive instrument, not initially designed to observe bright stars, and the instrument would overexpose like your cell-phone camera held towards the sun would,” Waldmann said. “In 2012, the scanning mode was introduced to address this. Essentially we now quickly move Hubble across the star and ‘smear’ the spectrum across the detector. This helps the overexposure issue, but makes the data analysis very difficult.”

An additional challenge came from 55 Cancri e’s close distance. It is orbiting a sun-like star that is only about 40 light-years away. Because the star is so bright, Waldmann said, the scan speed had to be much faster than what was used before. The team studied the situation and developed a method that can extract a viable signal from the data, a signal that was strong enough to detect elements in the small planet’s atmosphere.

Read more at Discovery News

The mystery about the Chelyabinsk superbolide continues three years later

In 2013 February 15, the approach of asteroid (367943) Duende to our planet was being closely monitored by both the public and the scientific community worldwide when suddenly a superbolide entered the atmosphere above the region of Chelyabinsk in Russia. Three years and hundreds of published scientific studies later, we are still looking for the origin of such unexpected visitor, that caused damage to hundreds of buildings and injuries to nearly 1,500 people. Finding the precise value of its speed as it touched the top of the atmosphere appears to be the key to determine the orbit of the parent body of the Chelyabinsk superbolide.

"Three years have passed since the Chelyabinsk (Russia) great scare and during this time more than two hundred research papers -50 in the last year- related directly or indirectly to the 19-m wide Chelyabinsk superbolide have been published in scientific peer-review journals," explains Carlos de la Fuente Marcos, co-author of one of these research works. Among these studies, there is a catalog of 960 video recordings, published by the journal Astronomy & Astrophysics, that includes material automatically recorded by security cameras, traffic cameras, dashcams -very popular in Russia- installed on-board of all types of vehicles, and manual recordings made with the video cameras and webcams of the many accidental witnesses of the impressive phenomenon who shared their experiences on the internet.

The images and diverse scientific data compiled during the event have allowed the calculation of the atmospheric entry trajectory of the meteoroid, which turned into a meteor when it crossed Earth's atmosphere, exploding at a height of 20 km and releasing 500 kilotons or energy, approximately thirty times the yield of the Hiroshima nuclear bomb. The shockwave generated by such an explosion caused damage out to a distance of 75 miles breaking the windows, and even the window frames in some cases, of hundreds of buildings and injuring 1,491 people mainly due to cuts inflicted by shattered and broken glass. Approximately five tons of meteoritic material reached the ground, including the 650-kg meteorite that was recovered by divers from the bottom of Lake Chebarkul.

The Chelyabinsk superbolide entry took place the same day, 2013 February 15, the asteroid (367943) Duende approached the Earth. Duende (discovered originally from Spain) passed nearly 27,700 km above the Earth's surface, well inside the boundaries of the ring of geosynchronous satellites but nearly perpendicular to it as expected, 16 hours after the Chelyabinsk superbolide explosion and the fall of the large meteorite on the Russian Lake Chebarkul.

At the beginning, it was thought that both events could be related and that the Chelyabinsk superbolide could have come from asteroid Duende itself or from a companion of this object, but when the orbits of both objects were analyzed and spectroscopic data of both asteroid Duende and the Chelyabinsk meteoritic material were studied in detail, the results obtained indicated that the two objects were completely independent and unrelated. It was a mere, albeit very unusual, coincidence in time of two spectacular cosmic events.

Where in space did the Chelyabinsk superbolide come from? "For a while, it was thought that asteroid (86039) 1999 NC43 was a good candidate for the parent body of the Chelyabinsk superbolide but after the publication of a detailed international study in the journal Icarus, it became clear that the Chelyabinsk impactor and the PHA 86039 (1999 NC43) were not part of the same object; from a dynamical and compositional point of view the relationship between both objects is too weak" explains de la Fuente Marcos.

During the last year, different orbital solutions for the asteroid that gave origin to the Chelyabinsk superbolide have been proposed; one of them has been computed by the Spanish astrodynamicists brothers Carlos and Raúl de la Fuente Marcos and Sverre J. Aarseth , scientist of the University of Cambridge (United Kingdom). Their work has been published by The Astrophysical Journal. These authors have used the recorded impact parameters of the Chelyabinsk superbolide to search for the orbit of its parent, or dynamically related, body by means of a numerical model validated using asteroid Duende's close approach data. "It is like when you are given a certain sample color to reproduce and a set of basic colors. You try all the mixtures, until you get the color that you want." compares de la Fuente Marcos.

The results of de la Fuente Marcos & Aarseth's model suggest that asteroid 2011 EO40 is a good dynamical relative of the parent body of the Chelyabinsk superbolide although there is no spectroscopic evidence linking genetically 2011 EO40 to Chelyabinsk; at least not yet. The common origin of both celestial objects is a possibility that cannot be discarded using the currently available evidence. The results obtained by de la Fuente Marcos and Aarseth indicate that the Chelyabinsk impactor likely passed a gravitational keyhole on 1982 February 15 during a close encounter with our planet at a distance shorter than 0.0015 AU. As a result of this close encounter, the initial 2011 EO40-like trajectory of the Chelyabinsk meteoroid was changed into the one that drove the meteoroid to strike the Earth over three decades later.

In addition, one of the main conclusions of this study, obtained after billions of simulations and a detailed statistical analysis, is that the main obstacle that prevents us from obtaining the correct orbit of the parent body of the Chelyabinsk superbolide is in the controversial value of its geocentric velocity at impact. This parameter has different values depending on the research study considered and this fact leads to slightly different pre-impact orbits.

As a matter of fact, the researchers admit that it is very difficult to know the exact asteroid that gave origin to the Chelyabinsk superbolide because in the neighborhood of our planet there is a tangled web of overlapping gravitational resonances that confines asteroids of heterogeneous, or diverse, origin to very similar orbits.

"These gravitational resonances create an environment like that of the great cities that attract people from different places and with very diverse backgrounds," says de la Fuente Marcos, who adds "Having two very similar orbits today does not imply that these orbits were also similar in the remote past."

This scenario is the one explored by the same authors in their latest research work to be published in March by the journal Monthly Notices of the Royal Astronomical Society, but that is already available online. "Here we demonstrate using statistics that among the objects close to the Earth (NEOs) there are groups of dynamical origin made of asteroids moving in similar orbits that may not be physically related or have the same chemical composition" explains de la Fuente Marcos.

Read more at Science Daily

Eternal 5D data storage could record the history of humankind

Scientists at the University of Southampton have made a major step forward in the development of digital data storage that is capable of surviving for billions of years.

Using nanostructured glass, scientists from the University's Optoelectronics Research Centre (ORC) have developed the recording and retrieval processes of five dimensional (5D) digital data by femtosecond laser writing.

The storage allows unprecedented properties including 360 TB/disc data capacity, thermal stability up to 1,000°C and virtually unlimited lifetime at room temperature (13.8 billion years at 190°C ) opening a new era of eternal data archiving. As a very stable and safe form of portable memory, the technology could be highly useful for organisations with big archives, such as national archives, museums and libraries, to preserve their information and records.

The technology was first experimentally demonstrated in 2013 when a 300 kb digital copy of a text file was successfully recorded in 5D.

Now, major documents from human history such as Universal Declaration of Human Rights (UDHR), Newton's Opticks, Magna Carta and Kings James Bible, have been saved as digital copies that could survive the human race. A copy of the UDHR encoded to 5D data storage was recently presented to UNESCO by the ORC at the International Year of Light (IYL) closing ceremony in Mexico..

The documents were recorded using ultrafast laser, producing extremely short and intense pulses of light. The file is written in three layers of nanostructured dots separated by five micrometres (one millionth of a metre).

The self-assembled nanostructures change the way light travels through glass, modifying polarisation of light that can then be read by combination of optical microscope and a polariser, similar to that found in Polaroid sunglasses.

Coined as the 'Superman memory crystal', as the glass memory has been compared to the "memory crystals" used in the Superman films, the data is recorded via self-assembled nanostructures created in fused quartz. The information encoding is realised in five dimensions: the size and orientation in addition to the three dimensional position of these nanostructures.

Professor Peter Kazansky, from the ORC, says: "It is thrilling to think that we have created the technology to preserve documents and information and store it in space for future generations. This technology can secure the last evidence of our civilisation: all we've learnt will not be forgotten.."

Read more at Science Daily

New semiconducting material could lead to much faster electronics

University of Utah engineers have discovered a new kind of 2D semiconducting material for electronics that opens the door for much speedier computers and smartphones that also consume a lot less power.

The semiconductor, made of the elements tin and oxygen, or tin monoxide (SnO), is a layer of 2D material only one atom thick, allowing electrical charges to move through it much faster than conventional 3D materials such as silicon. This material could be used in transistors, the lifeblood of all electronic devices such as computer processors and graphics processors in desktop computers and mobile devices. The material was discovered by a team led by University of Utah materials science and engineering associate professor Ashutosh Tiwari. A paper describing the research was published online Monday, Feb. 15, 2016 in the journal, Advanced Electronic Materials. The paper, which also will be the cover story on the printed version of the journal, was co-authored by University of Utah materials science and engineering doctoral students K. J. Saji and Kun Tian, and Michael Snure of the Wright-Patterson Air Force Research Lab near Dayton, Ohio.

Transistors and other components used in electronic devices are currently made of 3D materials such as silicon and consist of multiple layers on a glass substrate. But the downside to 3D materials is that electrons bounce around inside the layers in all directions.

The benefit of 2D materials, which is an exciting new research field that has opened up only about five years ago, is that the material is made of one layer the thickness of just one or two atoms. Consequently, the electrons "can only move in one layer so it's much faster," says Tiwari.

While researchers in this field have recently discovered new types of 2D material such as graphene, molybdenun disulfide and borophene, they have been materials that only allow the movement of N-type, or negative, electrons. In order to create an electronic device, however, you need semiconductor material that allows the movement of both negative electrons and positive charges known as "holes." The tin monoxide material discovered by Tiwari and his team is the first stable P-type 2D semiconductor material ever in existence.

"Now we have everything -- we have P-type 2D semiconductors and N-type 2D semiconductors," he says. "Now things will move forward much more quickly."

Now that Tiwari and his team have discovered this new 2D material, it can lead to the manufacturing of transistors that are even smaller and faster than those in use today. A computer processor is comprised of billions of transistors, and the more transistors packed into a single chip, the more powerful the processor can become.

Read more at Science Daily

Light used to measure the 'big stretch' in spider silk proteins

While working to improve a tool that measures the pushes and pulls sensed by proteins in living cells, biophysicists at Johns Hopkins say they've discovered one reason spiders' silk is so elastic: Pieces of the silk's protein threads act like supersprings, stretching to five times their initial length. The investigators say the tool will shed light on many biological events, including the shifting forces between cells during cancer metastasis.

"All other known springs, biological and nonbiological, lengthen in a way that is directly proportional to the force applied to them only until they have been stretched to about 20 percent of their original length," notes Taekjip Ha, Ph.D., the study's lead researcher. "At that point, you have to apply more and more force to stretch them the same distance as before. But the piece of the spider silk protein we focused on continues to stretch in direct proportion to the force applied until it reaches its maximal stretch of 500 percent."

Details of the research were published online in the journal Nano Letters on Feb. 5.

Ha, a Bloomberg Distinguished Professor of biophysics and biophysical chemistry at the Johns Hopkins University School of Medicine, says the new discovery came during follow-up to research he and his team, then at the University of Illinois at Urbana-Champaign, described in the journal Nature in 2010, work done in collaboration with cell biologists led by Martin Schwartz, then at the University of Virginia.

The Virginia team set up those experiments by inserting a repeating amino acid sequence -- taken from the spider silk protein known as flagelliform -- into a human protein called vinculin. Vinculin is responsible for internalizing forces outside a cell by bridging the cellular membrane and the actin network within the cell, making it an important mechanical communicator within the cell.

The scientists also flanked the flagelliform insert in vinculin with two fluorescent proteins to light up and "report" what was going on through fluorescence resonance energy transfer, or FRET. FRET occurs when one fluorescent molecule is close enough to another that it activates the second. So, when vinculin was relaxed within a cell, it "glowed" yellow, the color of the second fluorescent protein being activated by the first. As vinculin stretched, it began to glow blue -- the color of the first fluorescent protein -- because the lengthening distance between the two made FRET activation of the yellow protein impossible.

Using regular fluorescence microscopy, the scientists were able to watch the forces acting on vinculin in live cells in real time. But an issue remained: how to translate the changing colors into measurements of force "sensed" by vinculin.

That's where his team came in, says Ha. The researchers attached one end of modified vinculin to a glass plate and the other to a tether made of DNA with a small plastic bead at the end. They then pulled on the bead with what Ha describes as "chopsticks made of light," focusing a beam of light on a tiny spot nearby and generating an attractive force that pulled the bead toward the light source. That way, Ha says, his investigators could link the amount of FRET with the amount of force on vinculin, allowing them to measure the dynamic forces acting on proteins in live cells just by imaging them.

In that earlier study, the team inserted 40 flagelliform amino acids into vinculin, composed of eight repeats of the amino acid sequence GPGGA. In this new study, the scientists wanted to learn more about the flagelliform tool by varying its length, so they created inserts of five and 10 repeats to test alongside the original insert of eight. What they found is that the shortest insert was the most responsive to the widest range of forces, responding with linear increases in length to forces from 1 to 10 piconewtons. (Ha says that 1 piconewton is approximately the weight of a bacterium.)

The team wasn't expecting the spider silk inserts to show such linear behavior because, according to Ha, they don't form well-defined, three-dimensional structures. "Usually, unstructured proteins show disorderly, nonlinear behavior when we pull on them," says Ha. "The fact that these don't act that way means that they will be really useful tools for studying protein mechanics because their behavior is easy to understand and predict."

Read more at Science Daily

Record for fastest data rate set

Data stream.

A new record for the fastest ever data rate for digital information has been set by UCL researchers in the Optical Networks Group. They achieved a rate of 1.125 Tb/s as part of research on the capacity limits of optical transmission systems, designed to address the growing demand for fast data rates.

Lead researcher, Dr Robert Maher, UCL Electronic & Electrical Engineering, said: "While current state-of-the-art commercial optical transmission systems are capable of receiving single channel data rates of up to 100 gigabits per second (Gb/s), we are working with sophisticated equipment in our lab to design the next generation core networking and communications systems that can handle data signals at rates in excess of 1 terabit per second (Tb/s).

"For comparison this is almost 50,000 times greater than the average speed of a UK broadband connection of 24 megabits per second (Mb/s), which is the current speed defining "superfast" broadband. To give an example, the data rate we have achieved would allow the entire HD Games of Thrones series to be downloaded within one second."

The study, published today in Scientific Reports, used techniques from information theory and digital signal processing to custom build an optical communications system with multiple transmitting channels and a single receiver. As part of the EPSRC-funded UNLOC programme, the project set out to investigate ways to improve the optical network infrastructure to support the explosion of digital content, cloud and e-health services, as well as the ubiquitous connectivity of smart devices referred to as the Internet of Things (IoT).

Professor Polina Bayvel, the principal investigator of the UNLOC programme at UCL, said: "This result is a milestone as it shows that terabit per second optical communications systems are possible in the quest to reach ever higher transmission capacities in optical fibres that carry the vast majority of all data generated or received. A high-capacity digital communications infrastructure underpins the internet and is essential to all aspects of the digital economy and everyday lives."

The team determined the best way of encoding information in optical signals, taking into account the limitations of the transmitter and receiver. They then applied coding techniques commonly used in wireless communications, but not yet widely used in optical communications, to ensure the transmitted signals are adapted to distortions in the system electronics.

Using UNLOC's state-of-the-art lab facilities, the researchers built the new optical system and measured its performance. Fifteen channels, each carrying an optical signal of different wavelength were modulated using the 256QAM format typically used in cable modems, combined and sent to a single optical receiver for detection. By grouping the channels together, the team created a 'super-channel' which although not yet commercially available, is widely believed to be a way forward for the next generation of high-capacity communication systems.

Read more at Science Daily

Imaging with an 'optical brush'

The fibers of a new “optical brush” are connected to an array of photosensors at one end and left to wave free at the other.

Researchers at the MIT Media Lab have developed a new imaging device that consists of a loose bundle of optical fibers, with no need for lenses or a protective housing.

The fibers are connected to an array of photosensors at one end; the other ends can be left to wave free, so they could pass individually through micrometer-scale gaps in a porous membrane, to image whatever is on the other side.

Bundles of the fibers could be fed through pipes and immersed in fluids, to image oil fields, aquifers, or plumbing, without risking damage to watertight housings. And tight bundles of the fibers could yield endoscopes with narrower diameters, since they would require no additional electronics.

The positions of the fibers' free ends don't need to correspond to the positions of the photodetectors in the array. By measuring the differing times at which short bursts of light reach the photodetectors -- a technique known as "time of flight" -- the device can determine the fibers' relative locations.

In a commercial version of the device, the calibrating bursts of light would be delivered by the fibers themselves, but in experiments with their prototype system, the researchers used external lasers.

"Time of flight, which is a technique that is broadly used in our group, has never been used to do such things," says Barmak Heshmat, a postdoc in the Camera Culture group at the Media Lab, who led the new work. "Previous works have used time of flight to extract depth information. But in this work, I was proposing to use time of flight to enable a new interface for imaging."

The researchers reported their results today in Nature Scientific Reports. Heshmat is first author on the paper, and he's joined by associate professor of media arts and sciences Ramesh Raskar, who leads the Media Lab's Camera Culture group, and by Ik Hyun Lee, a fellow postdoc.

Travel time

In their experiments, the researchers used a bundle of 1,100 fibers that were waving free at one end and positioned opposite a screen on which symbols were projected. The other end of the bundle was attached to a beam splitter, which was in turn connected to both an ordinary camera and a high-speed camera that can distinguish optical pulses' times of arrival.

Perpendicular to the tips of the fibers at the bundle's loose end, and to each other, were two ultrafast lasers. The lasers fired short bursts of light, and the high-speed camera recorded their time of arrival along each fiber.

Because the bursts of light came from two different directions, software could use the differences in arrival time to produce a two-dimensional map of the positions of the fibers' tips. It then used that information to unscramble the jumbled image captured by the conventional camera.

The resolution of the system is limited by the number of fibers; the 1,100-fiber prototype produces an image that's roughly 33 by 33 pixels. Because there's also some ambiguity in the image reconstruction process, the images produced in the researchers' experiments were fairly blurry.

But the prototype sensor also used off-the-shelf optical fibers that were 300 micrometers in diameter. Fibers just a few micrometers in diameter have been commercially manufactured, so for industrial applications, the resolution could increase markedly without increasing the bundle size.

In a commercial application, of course, the system wouldn't have the luxury of two perpendicular lasers positioned at the fibers' tips. Instead, bursts of light would be sent along individual fibers, and the system would gauge the time they took to reflect back. Many more pulses would be required to form an accurate picture of the fibers' positions, but then, the pulses are so short that the calibration would still take just a fraction of a second.

"Two is the minimum number of pulses you could use," Heshmat says. "That was just proof of concept."

Read more at Science Daily